1. Field of the Invention
This invention relates to computer technology and more specifically to a circuit for use in a computer mass memory where MOS memory devices, read/write drivers, and clock and reset pulse drivers are configured on a printed circuit board so that, by changing the backplane wiring, this one mass storage module can be used for a wide variety of memory size and word length applications. For instance, the module described as the preferred embodiment can be reconfigured from 4,000 words of 18 bits in length (4K .times. 18) to 36,000 words to 2 bit length (36K .times. 2) using the same module and by rewiring the backplane. In general mathematical terms, devices each having P address lines and storing 2.sup.P .times. 1 bits, arranged into m rows of n columns can be reconfigured to store from 2.sup.P m words of n bits to 2.sup.P mn words of 1 bit depending on the backplane wiring.
2. Description of the Prior Art
Increasingly, computer manufacturers are implementing mass memory from MOS storage devices. A typical device is the 4,000 word by one bit device sold by Advance Memory Sytems, Inc. as Model No. AMS 6002.
Typically, a computer manufacturer has a particular memory configuration in mind while designing memory mass storage modules and designs the modules to the specific purpose. The result is a variety of mass storage modules requiring a number of test programs, assembly procedures, and printed circuit board layouts.
Attempts have been made to provide general purpose or "building block" memory modules which may allow for the variations in memory size and word bit length by using modules in parallel to increase the width and depth of the memory and, conversely, by using less than a full complement of devices in a module to produce a shorter than nominal word length. For instance, a module can be converted from an 18 bit board to a 4 bit board by removing fourteen of the eighteen columns of memory devices. Of course, depopulating a module by removing a significant fraction of the devices is an inefficient use of space on a module and therefore an inefficient use of mass memory storage volume.
There is, therefore, a need for a standard module which can be used variously for a larger number of smaller bit length words or a smaller number of larger bit length words without the necessity of any changes on the module itself.